Comparison of the in vivo and in vitro genotoxicity of glyphosate isopropylamine salt in three different organisms

Eco(geno)toxicity of the new commercial insecticide Platinum Neo, a mixture of the neonicotinoid thiamethoxam and the pyrethroid lambda-cyhalothrin

New mixtures of pesticides are being placed on the market to increase the spectrum of phytosanitary action. Thus, the eco(geno)toxic effects of the new commercial mixture named Platinum Neo, as well as its constituents the neonicotinoid Thiamethoxam and the pyrethroid Lambda-Cyhalothrin, were investigated using the species Daphnia magna, Raphidocelis subcapitata, Danio rerio, and Allium cepa L. The lowest- and no-observed effect concentration (LOEC and NOEC) were measured in ecotoxicological tests. While Thiamethoxam was ecotoxic at ppm level, Lambda-Cyhalothrin and Platinum Neo formulation were ecotoxic at ppb level. The mitotic index (MI), chromosomal aberrations and micronucleus [MN] frequency were measured as indicators of phytogenotoxicity in A. cepa plants exposed for 12 h to the different insecticides and their mixture under different dilutions. There were significant alterations in the MI and MN frequency in comparison with the A. cepa negative control group, with Thiamethoxam, Lambda-Cyhalothrin, and Platinum Neo treatments all significantly reducing MI and increasing MN frequency. Thus, MI reduction was found at 13.7 mg L-1 for Thiamethoxam, 0.8 μg L-1 for Lambda-Cyahalothrin, and 2.7:2 μg L-1 for Platinum Neo, while MN induction was not observed at 14 mg L-1 for Thiamethoxam, 0.8 μg L-1 for Lambda-Cyahalothrin, and 1.4:1 μg L-1 for Platinum Neo. The insecticide eco(geno)toxicity hierarchy was Platinun Neo > Lambda-Cyhalothrin > Thiamethoxam, and the organism sensitivity hierarchy was daphnids > fish > algae > A. cepa. Eco(geno)toxicity studies of new pesticide mixtures can be useful for management, risk assessment, and avoiding impacts of these products on living beings.

Tannic acid inhibits pain mediators, inflammation and oxidative stress in mice exposed to glyphosate-based herbicide

Chronic exposure to glyphosate-based herbicide (Gly) has been associated with neurological disorders. Tannic acid (TA) is an antioxidant with attenuating action against neuroinflammation-associated conditions. This study evaluated the effect of Gly on pain perception alongside antinociceptive and anti-inflammatory actions of TA in Gly-exposed mice. Male Swiss mice were randomly divided into six groups (n=8): control (distilled water 0.2 ml/kg), Gly (Gly 500 mg/kg), Pre-TA + Gly (TA 50 mg/kg pre-treatment, afterwards Gly-administered), TA + Gly (TA 50 mg/kg and Gly co-administered), Pre-AA + Gly (ascorbic acid (AA) 10 mg/kg pre-treatment, afterwards Gly-administered), and AA + Gly (AA 10 mg/kg and Gly co-administered). Mechanical, thermal, and chemical pain were evaluated six weeks post vehicle/drugs administrations orally, followed by brain biochemical measurements. TA treatment alleviated Gly-induced hyperalgesia in similar version to the values of control and AA groups by increasing significantly (p < 0.05) nociceptive thresholds. Moreover, TA-treatment significantly decreased malondialdehyde (MDA) and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) levels, significantly increased anti-inflammatory cytokines (IL-10, IL-4, and TGF-1β) levels, and antioxidant enzymes, catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) activities compared to Gly-treated mice (p < 0.05). Conclusively, TA treatment exerted antinociceptive and anti-inflammatory actions, possibly through its antioxidant and anti-inflammatory actions in Gly-exposed mice. Notably, TA pre-treatment showed a better response than TA and Gly co-administration. We propose the potential neuroprotective and ameliorative functions of TA in Gly-induced hyperalgesia. This merits further clinical research into protective roles of TA against pesticide-related conditions.

Mutagenic effects of a commercial glyphosate-based herbicide formulation on the soil filamentous fungus Aspergillus nidulans depending on the mode of exposure

Glyphosate-based herbicides (GBH) are the most used pesticides worldwide. This widespread dissemination raises the question of non-target effects on a wide range of organisms, including soil micro-organisms. Despite a large body of scientific studies reporting the harmful effects of GBHs, the health and environmental safety of glyphosate and its commercial formulations remains controversial. In particular, contradictory results have been obtained on the possible genotoxicity of these herbicides depending on the organisms or biological systems tested, the modes and durations of exposure and the sensitivity of the detection technique used. We previously showed that the well-characterized soil filamentous fungus Aspergillus nidulans was highly affected by a commercial GBH formulation containing 450 g/L of glyphosate (R450), even when used at doses far below the agricultural application rate. In the present study, we analysed the possible mutagenicity of R450 in A. nidulans by screening for specific mutants after different modes of exposure to the herbicide. R450 was found to exert a mutagenic effect only after repeated exposure during growth on agar-medium, and depending on the metabolic status of the tested strain. The nature of some mutants and their ability to tolerate the herbicide better than did the wild-type strain suggested that their emergence may reflect an adaptive response of the fungus to offset the herbicide effects. The use of a non-selective molecular approach, the quantitative random amplified polymorphic DNA (RAPD-qPCR), showed that R450 could also exert a mutagenic effect after a one-shot overnight exposure during growth in liquid culture. However, this effect was subtle and no longer detectable when the fungus had previously been repeatedly exposed to the herbicide on a solid medium. This indicated an elevation of the sensitivity threshold of A. nidulans to the R450 mutagenicity, and thus confirmed the adaptive capacity of the fungus to the herbicide.

Toxicity assessment and DNA repair kinetics in HEK293 cells exposed to environmentally relevant concentrations of Glyphosate (Roundup® Control Max)

Glyphosate is a systemic, non-selective, pre and post-emergence wide range herbicide. In 2015, IARC classified Glyphosate as "a probable carcinogenic agent for humans". The aim of this study was to evaluate the cytotoxicity and genotoxicity of the commercial formulation of glyphosate (Roundup® Control Max) at environmentally relevant concentrations and measure the potential effect of this herbicide over the cell capacity to repair DNA damage. HEK293 cells were exposed to 5 concentrations of Roundup® Control Max equivalent to 0.7; 7; 70; 700 and 3,500 μg/L glyphosate acid, for 1, 4 and 24 h. Cytotoxicity was quantified by the Trypan Blue staining method and by the MTT assay, while genotoxicity and evaluation of DNA damage repair kinetics were analyzed through the alkaline comet assay. In all treatments, cell viability was higher than 80%. The three highest glyphosate concentrations-70 μg/L, 700 μg/L, and 3,500 μg/L-increased levels of DNA damage compared to the control at the three exposure times tested. Finally, concerning the kinetics of DNA damage repair, cells initially exposed to 3,500 μg/L of glyphosate for 24 h were unable to repair the breaks in DNA strands even after 4 h of incubation in culture medium. The present study demonstrated for the first time that Roundup® Control Max may induce genetic damage and cause alterations in the DNA repair system in human embryonic kidney cells even at concentrations found in blood and breast milk of people exposed through residues of the herbicide in food, which values have been poorly assessed or not studied yet according to the existent literature.

Mapping the key characteristics of carcinogens for glyphosate and its formulations: A systematic review

Glyphosate was classified as a probable human carcinogen (Group 2A) by the International Agency for Research on Cancer (IARC) partially due to strong mechanistic evidence in 2015. Since then, numerous studies of glyphosate and its formulations (GBF) have emerged. These studies can be evaluated for cancer hazard identification with the newly described ten key characteristics (KC) of carcinogens approach. Our objective was to assess all in vivo, ex vivo, and in vitro mechanistic studies of human and experimental animals (mammals) that compared exposure to glyphosate/GBF with low/no exposure counterparts for evidence of the ten KCs. A protocol with our methods adhering to PRISMA guidelines was registered a priori (INPLASY202180045). Two blinded reviewers screened all in vivo, ex vivo, and in vitro studies of glyphosate/GBF exposure in humans/mammals reporting any KC-related outcome available in PubMed before August 2021. Studies that met inclusion criteria underwent data extraction conducted in duplicate for each KC outcome reported along with key aspects of internal/external validity, results, and reference information. These data were used to construct a matrix that was subsequently analyzed in the program R to conduct strength of evidence and quality assessments. Of the 2537 articles screened, 175 articles met inclusion criteria, from which we extracted >50,000 data points related to KC outcomes. Data analysis revealed strong evidence for KC2, KC4, KC5, KC6, KC8, limited evidence for KC1 and KC3, and inadequate evidence for KC7, KC9, and KC10. Notably, our in-depth quality analyses of genotoxicity (KC2) and endocrine disruption (KC8) revealed strong and consistent positive findings. For KC2, we found: 1) studies conducted in humans and human cells provided stronger positive evidence than counterpart animal models; 2) GBF elicited a stronger effect in both human and animal systems when compared to glyphosate alone; and 3) the highest quality studies in humans and human cells consistently revealed strong evidence of genotoxicity. Our analysis of KC8 indicated that glyphosate's ability to modulate hormone levels and estrogen receptor activity is sensitive to both exposure concentration and formulation. The modulations observed provide clear evidence that glyphosate interacts with receptors, alters receptor activation, and modulates the levels and effects of endogenous ligands (including hormones). Our findings strengthen the mechanistic evidence that glyphosate is a probable human carcinogen and provide biological plausibility for previously reported cancer associations in humans, such as non-Hodgkin lymphoma. We identified potential molecular interactions and subsequent key events that were used to generate a probable pathway to lymphomagenesis.

Glyphosate Toxicity: In Vivo, In Vitro, and Epidemiological Evidence

Glyphosate is the most applied agricultural chemical worldwide and has become nearly ubiquitous throughout the environment. Glyphosate is an effective herbicide because it disrupts the shikimate pathway, which is responsible for the synthesis of essential amino acids in plants and microorganisms. Given that there is no known target for glyphosate in higher animals, its toxicity to humans and other animals is heavily debated, especially after the 2015 IARC ruling that glyphosate is carcinogenic. Today, a growing body of literature shows in vitro, in vivo, and epidemiological evidence for the toxicity of glyphosate across animal species. With the application of glyphosate increasing globally, it is important to discuss these reports to enable a broader conversation on glyphosate toxicity and its impact on human and environmental health. Here, we summarize the recent glyphosate literature and discuss its implications.

Assessment of Genetic Damage Induced via Glyphosate and Three Commercial Formulations with Adjuvants in Human Blood Cells

There is considerable controversy regarding the genotoxicity of glyphosate (N-(phosphonomethyl) glycine). It has been suggested that the genotoxicity of this herbicide is increased by the adjuvants added to commercial formulations based on glyphosate. The effect of various concentrations of glyphosate and three commercial glyphosate-based herbicides (GBH) on human lymphocytes was evaluated. Human blood cells were exposed to glyphosates of 0.1, 1, 10 and 50 mM as well as to equivalent concentrations of glyphosate on commercial formulations. Genetic damage (p < 0.05) was observed in all concentrations with glyphosate and with FAENA and TACKLE formulations. These two commercial formulations showed genotoxicity that was concentration-dependent but in a higher proportion compared to pure glyphosate only. Higher glyphosate concentrations increased the frequency and range of tail lengths of some migration groups, and the same was observed for FAENA and TACKLE, while in CENTELLA the migration range decreased but the frequency of migration groups increased. We show that pure glyphosate and commercial GBH (FAENA, TACKLE and CENTELLA) gave signals of genotoxicity in human blood samples in the comet assay. The genotoxicity increased in the formulations, indicating genotoxic activity also in the added adjuvants present in these products. The use of the MG parameter allowed us to detect a certain type of genetic damage associated with different formulations.

Alterations in cell viability, reactive oxygen species production, and modulation of gene expression involved in mitogen-activated protein kinase/extracellular regulating kinase signaling pathway by glyphosate and its commercial formulation in hepatocellular carcinoma cells

Glyphosate (N-phosphonomethyl glycine) is a non-selective, organophosphate herbicide widely used in agriculture and forestry. We investigated the possible toxic effects of the glyphosate active compound and its commercial formulation (Roundup Star^®) in the human hepatocellular carcinoma (HepG2) cell line, including their effects on the cytotoxicity, cell proliferation, reactive oxygen species (ROS) levels, and expression of oxidative stress-related genes such as HO-1, Hsp70 Nrf2, L-FABP, and Keap1. MTT and NRU tests indicated that the IC₅₀ values of Roundup Star^® were 219 and 140 μM, respectively, and because glyphosate failed to induce cell death at the studied concentrations, an IC₅₀ value could not be determined for this cell line. Roundup Star at concentrations of 50 and 100 μM significantly increased (39.58% and 52%, respectively) cell proliferation, which 200 μM of glyphosate increased by 35.38%. ROS levels increased by 27.97% and 44.77% for 25 and 100 μM of Roundup Star and 32.74% and 38.63% for 100 and 200 μM of glyphosate exposure. In conclusion, Roundup Star and glyphosate significantly increased expression levels of selected genes related to the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway. This suggests that ROS production and the MAPK/ERK signaling pathway may be key molecular mechanisms in the toxicity of glyphosate in liver cells.

Toxic effects of glyphosate on the intestine, liver, brain of carp and on epithelioma papulosum cyprinid cells: Evidence from in vivo and in vitro research

Glyphosate (GLY) is the most widely used organophosphorus herbicide in agriculture. The present study aimed to analyze the comprehensive toxicological effects of GLY on juvenile common carp and an epithelioma papulosum cyprinid (EPC) cell line. In the in vivo experiments, exposure to GLY (5 and 15 mg/L) for 30 days induced liver inflammation and oxidative damage in common carp and changed the physical barrier of the intestine. Histopathological analysis of the intestine, liver, brain, and changes in oxidative stress biomarkers provided evidence of damage and immune system responses to GLY. Moreover, an inhibitory effect of 15 mg/L GLY on acetylcholinesterase (AChE) activity was found in the brain, which may be an important reason for the significant decrease in both swimming distance and average acceleration of common carp. Cell experiments showed that 0.65 and 3.25 mg/L GLY inhibited the viability of EPCs. Furthermore, oxidative DNA damage, mitochondrial dysfunction, and reactive oxygen species (ROS) production were observed in EPC cells following GLY exposure. Taken together, this study not only highlights the negative effects of GLY on common carp but also enriches the knowledge of the cytotoxicity mechanism to further clarify the comprehensive toxicity of GLY in common carp.

Overview of Environmental and Health Effects Related to Glyphosate Usage

Since the introduction of glyphosate (N-(phosphomethyl) glycine) in 1974, it has been the most used nonselective and broad-spectrum herbicide around the world. The widespread use of glyphosate and glyphosate-based herbicides is due to their low-cost efficiency in killing weeds, their rapid absorption by plants, and the general mistaken perception of their low toxicity to the environment and living organisms. As a consequence of the intensive use and accumulation of glyphosate and its derivatives on environmental sources, major concerns about the harmful side effects of glyphosate and its metabolites on human, plant, and animal health, and for water and soil quality, are emerging. Glyphosate can reach water bodies by soil leaching, runoff, and sometimes by the direct application of some approved formulations. Moreover, glyphosate can reach nontarget plants by different mechanisms, such as spray application, release through the tissue of treated plants, and dead tissue from weeds. As a consequence of this nontarget exposure, glyphosate residues are being detected in the food chains of diverse products, such as bread, cereal products, wheat, vegetable oil, fruit juice, beer, wine, honey, eggs, and others. The World Health Organization reclassified glyphosate as probably carcinogenic to humans in 2015 by the IARC. Thus, many review articles concerning different glyphosate-related aspects have been published recently. The risks, disagreements, and concerns regarding glyphosate usage have led to a general controversy about whether glyphosate should be banned, restricted, or promoted. Thus, this review article makes an overview of the basis for scientists, regulatory agencies, and the public in general, with consideration to the facts on and recommendations for the future of glyphosate usage.

Antigenotoxic Effect of Ascorbic Acid and Resveratrol in Erythrocytes of Ambystoma mexicanum, Oreochromis niloticus and Human Lymphocytes Exposed to Glyphosate

Glyphosate is a controversial herbicide. Its genotoxicity and presence in various ecosystems have been reported. The use of ascorbic acid and resveratrol could protect different organisms from glyphosate-induced genetic damage. In the present study, specific genetic damage induced by glyphosate was evaluated in erythrocytes of Oreochromis niloticus, Ambystoma mexicanum and human lymphocytes. Simultaneously, the antigenotoxic capacity of various concentrations of ascorbic acid and resveratrol was evaluated by means of pretreatment and simultaneous treatment protocols. The 0.03, 0.05 and 0.07 mM concentrations of glyphosate induced significant genotoxic activity (p < 0.05) in human lymphocytes and in erythrocytes of the species studied, and could cause genomic instability in these populations. The reduction in genetic damage observed in human lymphocytes exposed to high concentrations of glyphosate is only apparent: excessive genetic damage was associated with undetectable excessive tail migration length. A significant (p < 0.05) antigenotoxic effect of ascorbic acid and resveratrol was observed in all concentrations, organisms and protocols used. Both ascorbic acid and resveratrol play an important role in maintaining the integrity of DNA. Ascorbic acid in Oreochromis niloticus, Ambystoma mexicanum reduced glyphosate-induced genetic damage to a basal level. Therefore, our data indicate that these antioxidants could help preserve the integrity of the DNA of organisms exposed to glyphosate. The consumption of antioxidants is a useful tool against the genotoxicity of glyphosate.

A Review and Update with Perspective of Evidence that the Herbicide Glyphosate (Roundup) is a Cause of Non-Hodgkin Lymphoma

Glyphosate-based formulations (GBFs), such as Roundup, are the most heavily used herbicides in the world. In 2015, the International Agency for Research on Cancer (IARC) concluded that glyphosate and GBFs are probably carcinogenic to humans (group 2A), mainly for non-Hodgkin lymphoma (NHL). However, this finding has been controversial, and most pesticide regulatory agencies have not followed their lead. The purpose of this review was to examine the scientific literature linking exposure to glyphosate and GBFs to the development of NHL, with emphasis on new findings since publication of the IARC report. The epidemiologic studies provide ample evidence for an association between exposure to GBFs and an increased risk of NHL. Animal studies have shown that glyphosate is carcinogenic in rodents and causes NHL in mice. Mechanistic studies have demonstrated that glyphosate and GBFs are genotoxic to human lymphocytes, the normal cell of origin of NHL, both in vitro and in vivo. Genotoxic and other biological effects have also been shown in various animal and cell models with these agents even at low doses. A novel mechanism underlying the specificity of glyphosate for NHL, that is upregulation of the B-cell genome mutator enzyme activation-induced cytidine deaminase, has recently been demonstrated. These findings were evaluated holistically using the guidelines for evaluation of general causation set forth by Bradford Hill. This evaluation provides coherent and compelling evidence that glyphosate and GBFs are a cause of NHL in humans exposed to these agents. These findings should prompt new reviews by pesticide regulatory agencies around the world.

Determining the presence of glyphosate and glyphosate-tolerant events in maize and soybean food products in South Africa

Glyphosate is the most widely used herbicide in the world. In South Africa, glyphosate is predominantly used in the production of herbicide-tolerant (HT) maize and soybean. Considering that maize is a staple food and soybean an important source of protein, this study aimed to determine whether glyphosate is present in food products consumed by the general population in South Africa. Food products (81) were purchased from local supermarkets and screened for the presence of glyphosate and HT events using ELISA and real-time PCR, respectively. The majority of products contained glyphosate (66.7%) but at a level below the maximum residue limit. Glyphosate HT event(s) were detected in 70.4% of products but not associated with the presence of glyphosate in all products. This study has confirmed that South African consumers are exposed to low levels of glyphosate reported to cause genotoxic effects at the cellular level.

Micronucleus Formation Induced by Glyphosate and Glyphosate-Based Herbicides in Human Peripheral White Blood Cells

Glyphosate is the most commonly used herbicide around the world, which led to its accumulation in the environment and consequent ubiquitous human exposure. Glyphosate is marketed in numerous glyphosate-based herbicide formulations (GBHs) that include co-formulants to enhance herbicidal effect of the active ingredient, but are declared as inert substances. However, these other ingredients can have biologic activity on their own and may interact with the glyphosate in synergistic toxicity. In this study, we focused to compare the cytogenetic effect of the active ingredient glyphosate and three marketed GBHs (Roundup Mega, Fozat 480, and Glyfos) by investigating cytotoxicity with fluorescent co-labeling and WST-1 cell viability assay as well as genotoxicity with cytokinesis block micronucleus assay in isolated human mononuclear white blood cells. Glyphosate had no notable cytotoxic activity over the tested concentration range (0-10,000 μM), whereas all the selected GBHs induced significant cell death from 1,000 μM regardless of metabolic activation (S9). Micronucleus (MN) formation induced by glyphosate and its formulations at sub-cytotoxic concentrations (0-100 μM) exhibited a diverse pattern. Glyphosate caused statistically significant increase of MN frequency at the highest concentration (100 μM) after 20-h exposure. Contrarily, Roundup Mega exerted a significant genotoxic effect at 100 μM both after 4- and 20-h exposures; moreover, Glyfos and Fozat 480 also resulted in a statistically significant increase of MN frequency from the concentration of 10 μM after 4-h and 20-h treatment, respectively. The presence of S9 had no effect on MN formation induced by either glyphosate or GBHs. The differences observed in the cytotoxic and genotoxic pattern between the active principle and formulations confirm the previous concept that the presence of co-formulants in the formulations or the interaction of them with the active ingredient is responsible for the increased toxicity of herbicide products, and draw attention to the fact that GBHs are still currently in use, the toxicity of which rivals that of POEA-containing formulations (e.g., Glyfos) already banned in Europe. Hence, it is advisable to subject them to further comprehensive toxicological screening to assess the true health risks of exposed individuals, and to reconsider their free availability to any users.

Monitoring of glyphosate-DNA interaction and synergistic genotoxic effect of glyphosate and 2,4-dichlorophenoxyacetic acid using an electrochemical biosensor

Glyphosate (GLY) is a broad-spectrum herbicide used worldwide to control broadleaf sedge, and grass weeds to control non-specific vegetation. Although it was evaluated as non-toxic agent in 20th century, its carcinogenic and genotoxic potential has being intensively investigated all over the world in the last decade. Moreover, the combination of GLY and 2,4-dichlorophenoxyacetic acid (2,4-D) has been widely applied. Although genotoxicity of GLY has been evaluated in vivo studies, there is no report in the literature for the monitoring of in vitro biointeraction of GLY and double stranded DNA, or how effect the combination of GLY and 2,4-D onto DNA. Herein, an electrochemical biosensor platform was developed for detection of the pesticide-DNA interaction by using disposable pencil graphite electrodes (PGEs). First, voltammetric detection of the interaction between GLY and DNA was investigated and the electrochemical characterization of the interaction was achieved. Taking a step further, the synergistic genotoxic effect of the mixture of GLY and 2,4-dichlorophenoxyacetic acid (2,4-D) or the mixture of their herbicide forms onto DNA could be monitored. This effect was concentration dependent, and the herbicide of GLY or the use of mixture of herbicides of GLY and 2,4-D had more genotoxic effect than analytical grade of the active molecules, GLY and 2,4-D. The single-use PGEs provided to fabricate robust, eco-friendly and time saver recognition platform for monitoring of herbicide-DNA interaction with the sensitive and reliable results. It is expected that this study will lead to be designed miniaturized lab-on-a chip platforms for on-line analysis of the pesticide-nucleic acid interactions.

Chromosomal abnormalities and dysregulated DNA repair gene expression in farmers exposed to pesticides

Exposure to pesticides is considered a major factor underlying increased risk of hematological disorders in agricultural workers due to its carcinogenic potential. However, genotoxic impact of pesticides in DNA integrity of bone marrow stem cells (BMSC) of farmers exposed is not yet well known. We evaluated presence of chromosomal abnormalities (CA) and mRNA expression of DNA repair targets (ATM, BRCA1, BRCA2, RAD51, XRCC5, XRCC6, LIG4, CSA, CSB, XPA, XPC, XPG) in 90 bone marrow samples of farmers divided into three groups: commercial farming (CF), family farming (FF) and organic farming (OF). Our results showed that farmers in CF (72.7 %) and FF (27.3 %) groups had significantly higher values of CA when compared to OF group (0.0 %; p = 0.003). CF showed lower XPG (p = 0.008), CSA (p < 0.001), ATM (p = 0.036) and LIG4 (p = 0.004) mRNA expression than OF. FF presented lower XPG (p = 0.012) and LIG4 (p = 0.004) expression than OF. CF + FF individual with ≥12 years of exposure to pesticides showed decreased mRNA expression of XPC (p = 0.001), XPG (p = 0.010), CSB (p = 0.05), ATM (p = 0.030) and LIG4 (p = 0.044) than those who have been exposed for <12 years. CF + FF with CA showed a lower expression of BRCA2 when compared to CF + FF group without CA (p = 0.007). These results highlight that genotoxic exposure to pesticides negatively affects expression profile of important DNA repair genes in BMSC, favoring irreparable chromosomal lesions.

Roundup causes embryonic development failure and alters metabolic pathways and gut microbiota functionality in non-target species

BACKGROUND

Research around the weedkiller Roundup is among the most contentious of the twenty-first century. Scientists have provided inconclusive evidence that the weedkiller causes cancer and other life-threatening diseases, while industry-paid research reports that the weedkiller has no adverse effect on humans or animals. Much of the controversial evidence on Roundup is rooted in the approach used to determine safe use of chemicals, defined by outdated toxicity tests. We apply a system biology approach to the biomedical and ecological model species Daphnia to quantify the impact of glyphosate and of its commercial formula, Roundup, on fitness, genome-wide transcription and gut microbiota, taking full advantage of clonal reproduction in Daphnia. We then apply machine learning-based statistical analysis to identify and prioritize correlations between genome-wide transcriptional and microbiota changes.

RESULTS

We demonstrate that chronic exposure to ecologically relevant concentrations of glyphosate and Roundup at the approved regulatory threshold for drinking water in the US induce embryonic developmental failure, induce significant DNA damage (genotoxicity), and interfere with signaling. Furthermore, chronic exposure to the weedkiller alters the gut microbiota functionality and composition interfering with carbon and fat metabolism, as well as homeostasis. Using the "Reactome," we identify conserved pathways across the Tree of Life, which are potential targets for Roundup in other species, including liver metabolism, inflammation pathways, and collagen degradation, responsible for the repair of wounds and tissue remodeling.

CONCLUSIONS

Our results show that chronic exposure to concentrations of Roundup and glyphosate at the approved regulatory threshold for drinking water causes embryonic development failure and alteration of key metabolic functions via direct effect on the host molecular processes and indirect effect on the gut microbiota. The ecological model species Daphnia occupies a central position in the food web of aquatic ecosystems, being the preferred food of small vertebrates and invertebrates as well as a grazer of algae and bacteria. The impact of the weedkiller on this keystone species has cascading effects on aquatic food webs, affecting their ability to deliver critical ecosystem services. Video Abstract.

The impact and toxicity of glyphosate and glyphosate-based herbicides on health and immunity

Glyphosate, or N-phosphomethyl(glycine), is an organophosphorus compound and a competitive inhibitor of the shikimate pathway that allows aromatic amino acid biosynthesis in plants and microorganisms. Its utilization in broad-spectrum herbicides, such as RoundUp®, has continued to increase since 1974; glyphosate, as well as its primary metabolite aminomethylphosphonic acid, is measured in soils, water, plants, animals and food. In humans, glyphosate is detected in blood and urine, especially in exposed workers, and is excreted within a few days. It has long been regarded as harmless in animals, but growing literature has reported health risks associated with glyphosate and glyphosate-based herbicides. In 2017, the International Agency for Research on Cancer (IARC) classified glyphosate as "probably carcinogenic" in humans. However, other national agencies did not tighten their glyphosate restrictions and even prolonged authorizations of its use. There are also discrepancies between countries' authorized levels, demonstrating an absence of a clear consensus on glyphosate to date. This review details the effects of glyphosate and glyphosate-based herbicides on fish and mammal health, focusing on the immune system. Increasing evidence shows that glyphosate and glyphosate-based herbicides exhibit cytotoxic and genotoxic effects, increase oxidative stress, disrupt the estrogen pathway, impair some cerebral functions, and allegedly correlate with some cancers. Glyphosate effects on the immune system appear to alter the complement cascade, phagocytic function, and lymphocyte responses, and increase the production of pro-inflammatory cytokines in fish. In mammals, including humans, glyphosate mainly has cytotoxic and genotoxic effects, causes inflammation, and affects lymphocyte functions and the interactions between microorganisms and the immune system. Importantly, even as many outcomes are still being debated, evidence points to a need for more studies to better decipher the risks from glyphosate and better regulation of its global utilization.

Effects of glyphosate exposure on human health: Insights from epidemiological and in vitro studies

Glyphosate (GLY) is a broad-spectrum, post-emergent, non-selective and synthetic universal herbicide, whose commercial formulations are referred to as glyphosate-based-herbicides (GBHs). These chemicals and their metabolites can be found in soil, air, water, as well as groundwater and food products. This review summarizes to summarize current in vitro and epidemiological studies investigating the effects of GLY exposure on human health. Recent human cell studies have reported several GLY and GBH toxicological effects and have contributed to a better understanding of the deleterious consequences associated with their exposure. However, these detrimental effects are dependent on the cell type, chemical composition, as well as magnitude and time of exposure, among other factors. Moreover, the deleterious effects of GLY exposure on human health were observed in epidemiological studies; however, most of these studies have not determined the GLY dosage to confirm a direct effect. While GLY toxicity is clear in human cells, epidemiological studies investigating individuals exposed to different levels of GLY have reported contradictory data. Therefore, based on currently available in vitro and epidemiological data, it is not possible to confirm the complete safety of GLY use, which will require additional comprehensive studies in animal models and humans.

Comparative cyto- and genotoxicity assessment of glyphosate and glyphosate-based herbicides in human peripheral white blood cells

Glyphosate is the most heavily applied active compound of agricultural pesticides. It is solely used in more than 750 different glyphosate-based herbicide formulations (GBHs) that also contain other substances, mostly presumed as inert by regulatory agencies. The toxicity of formulations is currently assessed substance by substance, neglecting possible combined effects in mixtures and many of the findings regarding the toxic effects of glyphosate and GBHs to human cells are inconsistent. This is the first study to investigate and compare the cyto- and genotoxic potential of the active ingredient glyphosate and GBHs in human mononuclear white blood (HMWB) cells. HMWB cells were treated for 4 h at 37 °C with increasing concentrations (1-1000 μM) of glyphosate alone and in three GBHs (Roundup Mega, Fozat 480 and Glyfos) to test cytotoxic effect with fluorescent colabelling and genotoxic effect with comet assay. In addition, each concentration was tested with and without metabolic activation using human liver S9 fraction. We found that glyphosate alone does not induce significant cytotoxicity and genotoxicity over the tested concentration range. Contrarily, GBHs induced statistically significant cell death from 250 μM (Roundup Mega and Glyfos) and 500 μM (Fozat 480), as well as statistically significant increase of DNA damage from 500 μM (Roundup Mega and Glyfos) and 750 μM (Fozat 480); however, the latter observation may not be explained by direct DNA injuries, rather due to the high level of cell death (>70%) exerted by the formulations. Metabolic activation significantly increased the DNA damage levels induced by Glyfos, but not of the other GBHs and of glyphosate. The differences observed in the toxic pattern of formulations and the active principle may be attributed to the higher cytotoxic activity of other ingredients in the formulations or to the interaction of them with the active ingredient glyphosate. Hence, further investigation of formulations is crucial for assessing the true health risks of occupational and environmental exposures.

A glyphosate-based herbicide induces sub-lethal effects in early life stages and liver cell line of rainbow trout, Oncorhynchus mykiss

Most pesticides used in agriculture end up in the aquatic environment through runoff and leaching of treated crops. One of the most commonly used herbicides is glyphosate. This compound or its metabolites are frequently detected in surface water in Europe. In the present study, in vivo and in vitro studies were carried out using the early life stages of rainbow trout (Oncorhynchus mykiss) and the cell line RTL-W1 (a liver cell line from rainbow trout) to characterize the toxic effects of glyphosate at environmentally-realistic concentrations. Both studies were performed using the commercial formulation Roundup® GT Max, and technical-grade glyphosate for the in vitro study. Eyed-stage embryos were exposed for 3 weeks to sub-lethal concentrations (0.1 and 1 mg/L) of glyphosate using Roundup. Numerous toxicity endpoints were recorded such as survival, hatching success, larval biometry, developmental abnormalities, swimming activity, genotoxicity (formamidopyrimidine DNA-glycosylase Fpg-modified comet assay), lipid peroxidation (TBARS), protein carbonyls and target gene transcription. Concentrations neither affected embryonic or larval survival nor increased developmental abnormalities. However, a significant decrease was observed in the head size of larvae exposed to 1 mg/L of glyphosate. In addition, a significant increase in mobility was observed for larvae exposed to glyphosate at 0.1 mg/L. TBARS levels were significantly decreased on larvae exposed to 1 mg/L (a.i.), and cat and cox1 genes were differently transcribed from controls. DNA damage was detected by the Fpg-modified comet assay in RTL-W1 cell line exposed to the technical-grade glyphosate and Roundup formulation. The results suggest that chronic exposure to glyphosate, at environmental concentrations, could represent a potential risk for early life stages of fish.

In vitro evaluation of genomic damage induced by glyphosate on human lymphocytes

Glyphosate is an important broad-spectrum herbicide used in agriculture and residential areas for weed and vegetation control, respectively. In our study, we analyzed the in vitro clastogenic and/or aneugenic effects of glyphosate by chromosomal aberrations and micronuclei assays. Human lymphocytes were exposed to five glyphosate concentrations: 0.500, 0.100, 0.050, 0.025, and 0.0125 μg/mL, where 0.500 μg/mL represents the established acceptable daily intake value, and the other concentrations were tested in order to establish the genotoxicity threshold for this compound. We observed that chromosomal aberration (CA) and micronuclei (MNi) frequencies significantly increased at all tested concentrations, with exception of 0.0125 μg/mL. Vice versa, no effect has been observed on the frequencies of nuclear buds and nucleoplasmic bridges, with the only exception of 0.500 μg/mL of glyphosate that was found to increase in a significant manner the frequency of nucleoplasmic bridges. Finally, the cytokinesis-block proliferation index and the mitotic index were not significantly reduced, indicating that glyphosate does not produce effects on the proliferation/mitotic index at the tested concentrations.

The mechanism of DNA damage induced by Roundup 360 PLUS, glyphosate and AMPA in human peripheral blood mononuclear cells - genotoxic risk assessement

Glyphosate is the most heavily applied among pesticides in the world, and thus human exposure to this substance continues to increase. WHO changed classification of glyphosate to probably cancerogenic to humans, thus there is urgent need to assess in detail genotoxic mechanism of its action. We have assessed the effect of glyphosate, its formulation (Roundup 360 PLUS) and its main metabolite (aminomethylphosphonic acid, AMPA) in the concentration range from 1 to 1000 μM on DNA damage in human peripheral blood mononuclear cells (PBMCs). The cells were incubated for 24 h. The compounds studied and formulation induced DNA single and double strand-breaks and caused purines and pyrimidines oxidation. None of compounds examined was capable of creating adducts with DNA, while those substances increased ROS (including •OH) level in PBMCs. Roundup 360 PLUS caused damage to DNA even at 5 μM, while glyphosate and particularly AMPA induced DNA lesions from the concentration of 250 μM and 500 μM, respectively. DNA damage induced by glyphosate and its derivatives increased in order: AMPA, glyphosate, Roundup 360 PLUS. We may conclude that observed changes were not associated with direct interaction of xenobiotics studied with DNA, but the most probably they occurred through ROS-mediated effects.

Cytogenetic damage in peripheral blood cultures of Chaetophractus villosus exposed in vivo to a glyphosate formulation (Roundup)

Different concentrations of a glyphosate formulation, Roundup® Full II (66.2% glyphosate) were tested in culture peripheral blood of armadillo Chaetophractus villosus with cytogenetic biomarkers like mitotic index (MI), chromosomal aberrations (CA), sister chromatid exchange (SCE) and cell proliferation kinetics (CPK) by means of replication index. Adults animals of both sexes were exposed to RU at four concentrations ranging from 0.026 mL RU solution to 0.379 mL RU daily in oral treatment with the same volume (0.2 mL) during 7 days. We analyzed the induced damage at different times considering T0 as control value, one (T1), seven (T7) and 30 days (T30). One day after, only the higher concentration shows MI significant differences (p < 0.05), at T7 the frequency increases and at T30 it decreases reaching T0 values. The analysis of CA frequencies shows that only 0.106 mL RU/day exhibit significant differences vs T0 values. A great variability is expressed in the values of standard deviation (SD) and in the wide confidence intervals of the media. One day after treatments (T1) all four concentrations shows significant differences in SCE vs T0 values. Replication Index (RI) does not show significant differences. The dose-response behavior was not observed in either CA or SCE. The consistency of the findings obtained with the same biomarkers in vitro support the idea of expanding studies in order to characterize the risk doses for these mammals.

Oxidative stress, cholinesterase activity, and DNA damage in the liver, whole blood, and plasma of Wistar rats following a 28-day exposure to glyphosate

In this 28 day-study, we evaluated the effects of herbicide glyphosate administered by gavage to Wistar rats at daily doses equivalent to 0.1 of the acceptable operator exposure level (AOEL), 0.5 of the consumer acceptable daily intake (ADI), 1.75 (corresponding to the chronic population-adjusted dose, cPAD), and 10 mg kg-1 body weight (bw) (corresponding to 100 times the AOEL). At the end of each treatment, the body and liver weights were measured and compared with their baseline values. DNA damage in leukocytes and liver tissue was estimated with the alkaline comet assay. Oxidative stress was evaluated using a battery of endpoints to establish lipid peroxidation via thiobarbituric reactive substances (TBARS) level, level of reactive oxygen species (ROS), glutathione (GSH) level, and the activity of glutathione peroxidase (GSH-Px). Total cholinesterase activity and the activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were also measured. The exposed animals gained less weight than control. Treatment resulted in significantly higher primary DNA damage in the liver cells and leukocytes. Glyphosate exposure significantly lowered TBARS in the liver of the AOEL, ADI, and cPAD groups, and in plasma in the AOEL and cPAD group. AChE was inhibited with all treatments, but the AOEL and ADI groups significantly differed from control. Total ChE and plasma/liver ROS/GSH levels did not significantly differ from control, except for the 35 % decrease in ChE in the AOEL and ADI groups and a significant drop in liver GSH in the cPAD and 100xAOEL groups. AOEL and ADI blood GSH-Px activity dropped significantly, but in the liver it significantly increased in the ADI, cPAD, and 100xAOEL groups vs. control. All these findings show that even exposure to low glyphosate levels can have serious adverse effects and points to a need to change the approach to risk assessment of low-level chronic/sub-chronic glyphosate exposure, where oxidative stress is not necessarily related to the genetic damage and AChE inhibition.

Assessment of the health status and risk of genotoxic and cytotoxic damage in Argentinian adolescents living near horticultural crops

In some rural areas in Argentina, adolescents may be considered as a group indirectly exposed to agrochemicals because their parents plant small crops near their homes. This could become a health risk to children and adolescents who may be more sensitive to exposure to chemicals than adults. The objective of this study was to evaluate the health status of two different groups of Argentinian adolescents using biochemical parameters, dietary information, and cytogenetic biomarkers of genotoxicity and cytotoxicity. The study groups included 32 adolescents from Montecarlo, who were indirectly exposed to agrochemicals, and 30 unexposed adolescents from Exaltación de la Cruz. The values of total cholesterol, LDL cholesterol, triglycerides, gamma glutamyltransferase, and butyrylcholinesterase (BuChE) were higher (p < 0.05) in males from Exaltación de la Cruz compared with those from Montecarlo. The BuChE activity was also higher (p < 0.05) in females from this region. Furthermore, the consumption of citrus, vegetable-like fruits, tubers, and red meat was more frequent (p < 0.05) in Montecarlo. On the other hand, differences in frequency of biomarkers of genetic damage in lymphocytes were not found (p > 0.05). However, the cytome assay in buccal cells showed that karyorrhectic and pyknotic cells were more frequent (p < 0.05) in the Montecarlo group; whereas, the frequencies of cells with nuclear buds, condensed chromatin and karyolysis were higher (p < 0.05) in the Exaltación de la Cruz group. Despite the differences between the parameters and biomarkers evaluated, the adolescents of Montecarlo did not present health impairment probably due to the type and level of exposure to agrochemicals.

Screening of Pesticides with the Potential of Inducing DSB and Successive Recombinational Repair

A study was realized to ascertain whether eight selected pesticides would induce double strand breaks (DSB) in lymphocyte cultures and whether this damage would induce greater levels of proteins Rad51 participating in homologous recombination or of p-Ku80 participating in nonhomologous end joining. Only five pesticides were found to induce DSB of which only glyphosate and paraoxon induced a significant increase of p-Ku80 protein, indicating that nonhomologous end joining recombinational DNA repair system would be activated. The type of gamma-H2AX foci observed was comparable to that induced by etoposide at similar concentrations. These results are of importance since these effects occurred at low concentrations in the micromolar range, in acute treatments to the cells. Effects over longer exposures in actual environmental settings are expected to produce cumulative damage if repeated events of recombination take place over time.

Effects of low doses of glyphosate on DNA damage, cell proliferation and oxidative stress in the HepG2 cell line

We studied the toxic effects of glyphosate in vitro on HepG2 cells exposed for 4 and 24 h to low glyphosate concentrations likely to be encountered in occupational and residential exposures [the acceptable daily intake (ADI; 0.5 μg/mL), residential exposure level (REL; 2.91 μg/mL) and occupational exposure level (OEL; 3.5 μg/mL)]. The assessments were performed using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell proliferation, alkaline comet assay and cytokinesis-block micronucleus (CBMN) cytome assay. The results obtained indicated effects on cell proliferation, both at 4 and 24 h. The levels of primary DNA damage after 4-h exposure were lower in treated vs. control samples, but were not significantly changed after 24 h. Using the CBMN assay, we found a significantly higher number of MN and nuclear buds at ADI and REL after 4 h and a lower number of MN after 24 h. The obtained results revealed significant oxidative damage. Four-hour exposure resulted in significant decrease at ADI [lipid peroxidation and glutathione peroxidase (GSH-Px)] and OEL [lipid peroxidation and level of total antioxidant capacity (TAC)], and 24-h exposure in significant decrease at OEL (TAC and GSH-Px). No significant effects were observed for the level of reactive oxygen species (ROS) and glutathione (GSH) for both treatment, and for 24 h for lipid peroxidation. Taken together, the elevated levels of cytogenetic damage found by the CBMN assay and the mechanisms of primary DNA damage should be further clarified, considering that the comet assay results indicate possible cross-linking or DNA adduct formation.

DNA damage and methylation induced by glyphosate in human peripheral blood mononuclear cells (in vitro study)

Glyphosate is a very important herbicide that is widely used in the agriculture, and thus the exposure of humans to this substance and its metabolites has been noted. The purpose of this study was to assess DNA damage (determination of single and double strand-breaks by the comet assay) as well as to evaluate DNA methylation (global DNA methylation and methylation of p16 (CDKN2A) and p53 (TP53) promoter regions) in human peripheral blood mononuclear cells (PBMCs) exposed to glyphosate. PBMCs were incubated with the compound studied at concentrations ranging from 0.1 to 10 mM for 24 h. The study has shown that glyphosate induced DNA lesions, which were effectively repaired. However, PBMCs were unable to repair completely DNA damage induced by glyphosate. We also observed a decrease in global DNA methylation level at 0.25 mM of glyphosate. Glyphosate at 0.25 mM and 0.5 mM increased p53 promoter methylation, while it did not induce statistically significant changes in methylation of p16 promoter. To sum up, we have shown for the first time that glyphosate (at high concentrations from 0.5 to 10 mM) may induce DNA damage in leucocytes such as PBMCs and cause DNA methylation in human cells.

Is it time to reassess current safety standards for glyphosate-based herbicides?

Use of glyphosate-based herbicides (GBHs) increased ∼100-fold from 1974 to 2014. Additional increases are expected due to widespread emergence of glyphosate-resistant weeds, increased application of GBHs, and preharvest uses of GBHs as desiccants. Current safety assessments rely heavily on studies conducted over 30 years ago. We have considered information on GBH use, exposures, mechanisms of action, toxicity and epidemiology. Human exposures to glyphosate are rising, and a number of in vitro and in vivo studies challenge the basis for the current safety assessment of glyphosate and GBHs. We conclude that current safety standards for GBHs are outdated and may fail to protect public health or the environment. To improve safety standards, the following are urgently needed: (1) human biomonitoring for glyphosate and its metabolites; (2) prioritisation of glyphosate and GBHs for hazard assessments, including toxicological studies that use state-of-the-art approaches; (3) epidemiological studies, especially of occupationally exposed agricultural workers, pregnant women and their children and (4) evaluations of GBHs in commercially used formulations, recognising that herbicide mixtures likely have effects that are not predicted by studying glyphosate alone.

Occupational and life-style factors-acquired mutagenicity in agric-workers of northeastern Brazil

Pesticides are a complex mixture of chemicals used to protect crops from a number of pests and diseases. They have been considered as potential mutagenic agents. This study aims at evaluation of the mutagenic effect of pesticide exposure to agricultural workers through chromosomal aberrations (CA) and micronucleus (MN) assay in peripheral blood lymphocytes and oral mucosal cells, respectively. The exposed group was consisted with 97 farmers, while the control (un-exposed) group consisted of 55. The results showed a significant (p < 0.05) increase in frequency of CA and MN in the exposed group. Both CA and MN profiles were linked to a significant (p < 0.05) co-relation with the confounding factors such as smoking habits, alcohol, vegetables, tea/coffee, vitamins, and sweetener consumptions. More cytogenetic events were denoted in smoking and alcohol consumption as well as non-personal protective equipment (non-PPE) and low/no vegetables user farmers. In conclusion, a deficiency of dietary and medicaments-derived antioxidants, while consumption of alcohol and tobacco, as well as effects of radiation, heavy metal poisoning (especially from sweeteners), and non-PPE using habits, may contribute cytogenetic damage to the workers.